Re: [RFC PATCH v2 0/3] sched/fair: introduce new scheduler group type group_parked

Tobias Huschle
2025-02-20T10:55:27Z

On 18/02/2025 06:58, Shrikanth Hegde wrote:
[...]
>>
>> There are a couple of issues and corner cases which need further
>> considerations:
>> - rt & dl:      Realtime and deadline scheduling require some additional
>>                  attention.
>
> I think we need to address atleast rt, there would be some non percpu
> kworker threads which need to move out of parked cpus.
>

Yea, sounds reasonable. Would probably make sense to go next for that one.

>> - ext:          Probably affected as well. Needs some conceptional
>>                  thoughts first.
>> - raciness:     Right now, there are no synchronization efforts. It needs
>>                  to be considered whether those might be necessary or if
>>                  it is alright that the parked-state of a CPU might
>> change
>>                  during load-balancing.
>>
>> Patches apply to tip:sched/core
>>
>> The s390 patch serves as a simplified implementation example.
>
>
> Gave it a try on powerpc with the debugfs file. it works for
> sched_normal tasks.
>

That's great to hear!

>>
>> Tobias Huschle (3):
>>    sched/fair: introduce new scheduler group type group_parked
>>    sched/fair: adapt scheduler group weight and capacity for parked CPUs
>>    s390/topology: Add initial implementation for selection of parked CPUs
>>
>>   arch/s390/include/asm/smp.h    |   2 +
>>   arch/s390/kernel/smp.c         |   5 ++
>>   include/linux/sched/topology.h |  19 ++++++
>>   kernel/sched/core.c            |  13 ++++-
>>   kernel/sched/fair.c            | 104 ++++++++++++++++++++++++++++-----
>>   kernel/sched/syscalls.c        |   3 +
>>   6 files changed, 130 insertions(+), 16 deletions(-)
>>
>